all contacts.swift

lazy var contacts: [CNContact] = {
        let contactStore = CNContactStore()
        
        contactStore.requestAccess(for: .contacts, completionHandler: { (granted, error) in
            guard granted else {
                let alert = UIAlertController(title: "Can't access contact", message: "Please go to Settings to enable contact permissions.", preferredStyle: .alert)
                alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
                //TODO: link directly to settings app here.
                self.present(alert, animated: true, completion: nil)
                return
            }
        })
        
        // Get all the containers
        var allContainers: [CNContainer] = []
        do {
            allContainers = try contactStore.containers(matching: nil)
        } catch {
            print("Error fetching containers")
        }
        var results: [CNContact] = []
        
        // Iterate all containers and append their contacts to our results array
        for container in allContainers {
            let fetchPredicate = CNContact.predicateForContactsInContainer(withIdentifier: container.identifier)
            guard let keys = self.keysToFetch else {return []}
            do {
                let containerResults = try contactStore.unifiedContacts(matching: fetchPredicate, keysToFetch: keys)
                results.append(contentsOf: containerResults)
            } catch {
                print("Error fetching results for container")
            }
        }
        return results
    }()